Propagation of Streptosolen jamesonii (Benth.) Miers by stem cutting treated with IBA in different substrates

The mamalade shrub [Streptosolen jamesonii (Benth.) Miers] is an ornamental species with great potential of use in gardens; these plants have an intense contrast of colors between flowers and leaves and their flowering occurs in practically all the seasons of the year. This plant is propagation mainly by stem cuttings, but the propagation vegetative of this plant is still poorly known. Knowledge about auxin and substrate actuations on rooting may be useful for the cultivation and promotion of the popularization of these plants for garden ornamentation purposes. Therefore, this work aimed evaluated the effect of indolbutiric acid (IBA) and substrates on stem rooting and quality of marmalade bush plants. The experimental design was the completely randomized, in a 5x3 factorial scheme, with eight replications and one stem cut per plot. Factor A consisted of four concentrations of IBA 500; 1000; 2000 and 3000 mg L-1 and a control 0 mg L-1 (only distilled water); the B factor was constituted of substrates: vermiculite, sand and commercial substrate Plantmax®. Each herbaceous cutting was standardized by length, measuring 10 cm and six leaves. The treatment was performed submerging the base of cutting, 3 cm in length, in solution of IBA for 1 min and disposed in substrates vermiculite, sand or commercial substrate. After 30 days were evaluated the percentage of rooting and surviving of cutting, the number of roots and shoots, the length of roots and shoots; the length of roots and shoots and the fresh weight of roots and shoots were evaluated. The IBA concentrations or the substrates do not affect the rooting or survival of the cuttings, however, better quality plantlets are obtained when the cuttings are treated with 750 to 1456 mg L-1 IBA in commercial substrates where the highest number of roots and the greater development of root and new shoots.